Igniter nozzle anti-coking device



United States Patent 3,030,774 IGNITER NOZZLE ANTI-COKING DEVICE Frederick W. Henning, Merriam, Kans., and Robert J.

Gerardi, Kansas City, Mo., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed May 14, 1959, Ser. No. 813,322 2 Claims. (Cl. 60-3954) The present invention relates to an igniter nozzle anticoking device and more particularly to an igniter nozzle anti-coking device for use in turbojet engines which prevents droplets of fuel from clogging the igniter nozzle.

It has been found desirable when using heavy fuels in turbojet engines to provide a low capacity igniter nozzle to produce a finely atomized fuel spray for starting. The efficiency of such a system, however, has been negated to a large extent by the tendency of droplets of fuel burning in the combustion chamber to hit the end of the igniter nozzle and clog it. Another disadvantage of conventional ignition systems is that the high velocity air flow in the secondary air passage between the combustion housing and the combustion chamber outer liner impinges on the igniter nozzle preventing relighting at altitudes which freeze the ignition fuel in the nozzle.

The present invention contemplates the provision of a tubular shell around the igniter nozzle to which is introduced a small quantity of pressurized fluid. The igniter fuel mixes with the pressurized fluid in the shell and is ejected into the combustion chamber in an atomized spray, the action of the pressurized fluid preventing droplets of fuel from impinging on and clogging the nozzle. The tubular shell which extends between the combustor housing and combustion chamber outer liner also partially insulates the nozzle from the secondary air flow which would otherwise freeze the igniter fuel in the nozzle at high altitudes.

Accordingly, it is a primary purpose of the instant invention to provide means for preventing clogging of igniter nozzles used in conjunction with turbojet engines.

Another object is to provide a means for introducing igniter fuel into the combustion chamber of a turbojet engine in a pressurized spray whereby droplets of fuel are prevented from impinging on and clogging the igniter nozzle.

A final object of the invention is a provision of a shield for the igniter nozzle used in conjunction with turbojet engines which prevents igniter fuel from freezing in the nozzle at high altitudes.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing which illustrates a side elevation, partly in section, of a preferred embodiment of the invention.

Referring now to the drawing, there is shown an igniter nozzle 5 having at one end an injection orifice 6 and at the other end a fuel inlet conduit 7. The nozzle extends through an aperture 8 in the combustor housing 9 into the secondary air passage 10 to a point where the orifice 6 lies within an aperture 11 in the outer liner 12 of the turbojet combustion chamber 13. The nozzle is enclosed by a tubular shell 14 having a fluid inlet 15 in the sidewall of the shell and a smaller fluid outlet 16 in the end of the shell, the shell and nozzle being secured to the outer surface of the combustor housing by means of an annular collar 17. The inner portion 18 of the igniter nozzle has a diameter and length slightly less than the inner diameter and length of the shell thereby forming a small space 19 surrounding the nozzle portion 18, the distance between the end of the nozzle and the shell be- "ice 2 ing less than the distance between the sides of the nozzle and shell.

In operation, a small quantity of air flowing in the secondary air passage 10 is intercepted by the inlet 15 thereby pressurizing the space 19 around the inner end of the nozzle. The relatively small space between the nozzle end and the shell as compared to the space between the inner Wall of the shell and the sides of the nozzle meters a high velocity air flow through the outlet 16 carrying with it the igniter fuel. The high velocity air flow prevents burning droplets of fuel from impinging on and clogging the orifice 6 of the nozzle.

Since the tubular shell 14 partially insulates the nozzle from the air flow through the passageway 10, freezing of the igniter fuel in the nozzle at high altitudes is prevented. Thus, the provision of the shell permits relighting of the fuel at higher altitudes than heretofore possible.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. A device for preventing clogging and freezing of an igniter nozzle used in conjunction with turbojet engines comprising an igniter nozzle having an outlet orifice, fluid supply means formed by a shell surrounding said nozzle, said shell also providing insulation for said nozzle to prevent freezing of the fuel Within said nozzle, said nozzle being spaced from the inner Wall of said shell, a fluid inlet in said shell and a fluid outlet in said shell adjacent said orifice, said fluid inlet being of a larger diameter than said outlet, the distance between the sides of the nozzle and the inner vertical Wall of said shell being greater than the distance between said orifice and said fluid outlet whereby the velocity of said fluid is increased prior to its striking the face of said nozzle and thereby keeps the nozzle clean of unburned fuel particles.

2. A combination igniter nozzle, anti-clogging and antifreezing device for use in turbojet engines having a combustion chamber, a combustion chamber outer liner and a combustor housing spaced from said liner forming an air passage comprising an igniter nozzle extending through an aperture in said combustor housing into the space between said housing and liner, an orifice in one end of said nozzle, said one end of the nozzle lying within an aperture in said liner, fuel supply means connected to the other end of said nozzle, a tubular shell surrounding said nozzle, said shell extending through the aperture in said housing and liner and providing insulation for said nozzle to prevent freezing of the fuel within said nozzle at high altitudes, a portion of said nozzle, including said one end, being spaced from the inner wall of said shell, an inlet aperture in the side wall of said shell within the space between said housing and liner, an outlet in the end of said shell adjacent said orifice, said inlet being of larger diameter than said outlet, means securing said shell and nozzle to said housing, the distance between said inlet and the sides of said nozzle being greater than the distance between the outlet and said orifice whereby air entering said inlet will undergo a velocity increase due to the reduction in area and ejected from said outlet under increased velocity to prevent burning droplets of fuel from clogging said orifice.

References Cited in the file of this patent UNITED STATES PATENTS 2,540,642 Allen et a1 Feb. 6, 1951 2,926,495 Benson et al. Mar. 1, 1960 FOREIGN PATENTS 686,425 Great Britain Jan. 21, 1953 694,483 Great Britain July 22, 1953 

